Material such as scree, gravel, sand, or clay formed by weathering. Through the air, debris is transported by saltation and deflation; in water, debris moves by rolling, by saltation, in solution, and in suspension. Debris can be carried on a glacier—supraglacially—within a glacier—englacially—or subglacially. Debris entrainment is the process whereby ice picks up material: by the freezing of basal ice to the bed as the ice flows forward (Cuffy et al. (2000) Geology 28, 4); through the drag between ice and bedrock particles; via the closure of debris-filled basal cavities in the ice; by the refreezing of meltwater; and on the glacier surface. Debris flow is the very rapid downslope movement of saturated material, guided by stream channels, and both less deep seated and rarer than a landslide. See Blikra and Nemec (1998) Sedimentol. 45 on debris flow, deposits, and controls on debris-flow activity, Tunusluoglu et al. (2007) Nat. Haz. Earth Sys. Sci. 7 on artificial neural networks and debris flows, and Hartshorn and Lewkowicz (2000) Zeitschrift 44.